The family of poly(ADP-ribose)polymerases (PARP) includes approximately 18 proteins, which all display a certain level of homology in their catalytic domain but differ in their cellular functions (Ame et al., BioEssays., 26(8), 882-893 (2004)). PARP-1 and PARP-2 are unique members of the family, in that their catalytic activities are stimulated by the occurrence of DNA strand breaks.
PARP has been implicated in the signaling of DNA damage through its ability to recognize and rapidly bind to DNA single or double strand breaks (D'Amours, et al., Biochem. J., 342, 249-268 (1999)). It participates in a variety of DNA-related functions including gene amplification, cell division, differentiation, apoptosis, DNA base excision repair as well as effects on telomere length and chromosome stability (d'Adda di Fagagna, et al., Nature Gen., 23(1), 76-80 (1999)).
Syntheses of dihydropyridophthalazinone derivatives are disclosed in U.S. Patent Publication No. US 2010/0035883 A1, the content of which is hereby incorporated by reference in its entirety. However, the synthetic routes disclosed in US 2010/0035883 A1 present scale-up challenges, inter alia. Accordingly, there exists a need to provide improved synthetic routes to this class of compounds, and particularly for 5-fluoro-8-(4-fluorophenyl)-9-(1-methyl-1H-1,2,4-triazol-5-yl)-8,9-dihydro-2H-pyrido[4,3,2-de]phthalazin-3(7H)-one and its stereoisomers.